A COB (Chip On Board) light-emitting device in which light-emitting elements, such as LED (light-emitting diode) elements, are mounted on a general-purpose substrate, such as a ceramic substrate or a metal substrate, is known. In such a light-emitting device, white light or the like is obtained depending on the intended use by sealing, for example, LED elements that emit blue light with a resin containing a phosphor, and mixing light obtained by exciting the phosphor with the light from the LED elements.
As light-emitting elements of a light-emitting device used for a general lighting purpose, blue LEDs that emit blue light, UV elements, or the like are suitable because it is easy to produce a white emission color. In addition, as a resin material for sealing such light-emitting elements, a silicone is often used by due to an emission color of light-emitting elements to be used.
As light sources for lighting to replace light bulbs and fluorescent lamps, a lighting device using light-emitting elements (LED elements) is adopted recently. LED elements consume lower amount of power compared to light bulbs and the like, but have low directivity because of being point light sources, and thus, in an LED lighting device, about several tens to several hundred LED elements are mounted, and these elements are sealed with a translucent resin, so that a light-emitting surface having uniform brightness is formed. For example, in Patent Literature 1 and 2, a light-emitting device having a light-emitting surface formed by sealing light-emitting elements mounted on a substrate with a translucent resin material is described.
In addition, Patent Literature 3 describes a light-emitting device in which light-emitting elements mounted on a base material having, on a surface thereof, a conductor layer connected to the outside are sealed. The light-emitting device includes a phosphor layer arranged above the light-emitting elements and a resin layer which is in contact with both the phosphor layer and the conductor layer and has dispersed heat transfer particles to improve heat generation from phosphor particles.
In addition, a manufacturing method of such a light-emitting device is known in which a phosphor dispersed in a resin is made to be precipitated, and then, the resin is hardened, in order to suppress variation in chromaticity, for example. For example, Patent Literature 4 describes a manufacturing method of a light-emitting element package including the steps of forming a repellent agent pattern on a substrate, mounting LED chips on the inside of the repellent agent pattern on the substrate, applying a sealing resin in which a phosphor is kneaded on the inside of the repellent agent pattern, and making the phosphor in the sealing resin be precipitated in a windless state.